This invention relates to colored resinous articles which meet Federal requirements for direct contact with food, and more particularly to a decorative grass which enables candies to be placed directly thereon without the need of separate overwrapping.
More specifically, the invention relates to pigmented color formulations which can be mixed with resinous products to provide uniform coloration thereof and produce a colored resinous product which can be utilized safely as a direct contact food packaging material.
Many resins are coming into widespread use for food packaging. Polyolefins such as polyethylene have been used extensively as the use of these resins have considerable economy, increased transparency, ease of handling economics such as lower shipping cost and less breakage and product protection in that they act as a very effective barrier to oxygen and thus assist in preservation of the food content. Polyolefin resins have also been used as a decorative packaging material for food products, such as the decorative grass disclosed in our U.S. Pat. No. 4,199,627. However, while resin packaging has proven to be economical and efficient in preserving food, and in the case of the decorative grass disclosed in our patent, capable of being manufactured into an improved product, there are no acceptable colorants which are approved for use in direct contact food packaging and at the same time compatible with the principal resins formed into the packaging materials. For instance, when polyolefins formed into decorative grasses are colored with conventional colorants and utilized for the purpose of holding a variety of candies, the candies must be separately wrapped to prevent direct contact of the food with the colored resinous material. The separate overwrapping adds significantly to the total cost of the finished package or product and, therefore, it would be of great economical advantage as well as a significant safety feature to color a resin packaging material with a colorant formulation which meets Federal requirements for direct food contact packaging.
The incorporation of dyes into resin base materials used for cosmetics are, of course, well-known to those in the art as exemplified by U.S. Pat. Nos. 3,148,125, issued Sept. 8, 1964, and 3,937,811, issued Feb. 10, 1976. U.S. Pat. No. 3,677,691, issued July 18, 1972, discloses a process for the conversion of water soluble dyestuffs which are approved for use in cosmetics, pharmaceuticals and food products into lypophilic colors which are readily dissolved in various oils. This patent was concerned with the fact that available oil soluble color compositions which were approved by the Food and Drug Administration were being drastically reduced in number, and that it became important for manufacturers of dyes and color additives to investigate the possibility of conversion of generally established non-toxic water soluble, oil insoluble dyes and pigments to a lypophilic state. U.S. Pat. No. 4,102,848, issued July 25, 1978, to Koch et al. is directed to coloring resin packaging materials and was concerned that at the time of the patent, there were no acceptable organic dyestuffs which were approved for use in contact with foods and beverages, medicinal products or cosmetics and at the same time compatible with many of the principal resins used for packaging. Accordingly, an object of the patent is to overcome disadvantages in the art of coloring plastic food, drug and cosmetic containers and to present to the art a resinous molding composition which is not only acceptable as safe for contact with consummable items but which resin is also colored in various shades and transparent to any degree desired. The patent accomplishes the object by first complexing the water soluble, resin insoluble FD&C dyestuffs with a polyhydric alcohol and subsequently the higher fatty acid ester decaglycerol tetraoleate in the presence of heat whereby it is possible to prepare a uniformly colored resin solution or paste which can be further cured to form a color tinted transparent plastic film or sheet useful in packaging. Briefly, U.S. Pat. No. 4,102,848 has succeeded to dissolve dyes into a substance, and incorporate that substance into a resinous material in which the dyes are usually not soluble.
While the Koch et al. invention may be successful, it would be advantageous to color resinous articles with pigment dispersions rather than the dye formulations disclosed in this patent. Pigment dispersions because of their insolubility, tend to migrate and bleed less than most dye formulations, such that color transfer onto other surfaces is substantially eliminated. Pigment dispersions typically do not fade as much as dye colorants when exposed to light over substantial periods of time. Further, pigment dispersions are more stable at higher temperatures in which most plastic extruding or molding devices operate, making processing of the resinous articles more feasible and economical. While dye formulations provide colored resinous articles of good transparency, pigment dispersions which are finely ground can often approach the transparency of dyed formulations.
Attempts have been made to disperse organic pigments that meet FDA specifications for food packaging materials and FD&C pigments into non-toxic oil such as mineral oil, but such attempts have been very difficult. Substances such as dipropylene glycol or dioctyl phthalate are very good dispersers, of pigments, but they are not very suitable in food packaging because of possible toxicity problems. On the other hand, the non-toxic oils such as mineral oil and some of the vegetable oils do not disperse pigments very well, resulting in that the pigments could not be broken down into small particles and form a uniform dispersion. When incorporated into resinous articles, the large particles of pigment tended to settle out, resulting in plastics colored from this type of formulation exhibiting poor strength of color, an uneven gritty consistency, and very poor transparency.
It is an object of the present invention to provide not only a resinous article which is acceptable as safe for direct contact with food stuffs, but which resin is also colored in various shades and transparencies to any degree desired.
It is a further object of the invention to provide a decorative grass packaging material which meets Federal requirements for direct food contact packaging, thereby eliminating the expense of overwrapping the food before contact with the packaging material and eliminates the hazard involved when unwrapped food is inadvertently or unknowingly placed on the decorative resin grass.
It is still another object of the invention to provide color formulation in which finely ground pigment is dispersed into non-toxic substances which are normally very poor dispersing agents, but which are compatible with resinous materials.
These and several other objects of the invention will become clear upon further consideration of the description of the invention set forth in the following general description and several selected and preferred modes of its practice.